This invention relates to an electrostatic copying apparatus having a photosensitive drum, more specifically to an electrostatic copying apparatus with a vertically separated casing.
Generally, an electrostatic copying apparatus is provided with a photosensitive drum having a photosensitive layer on its outer peripheral surface. It is known that the copying performance of a copier with a photosensitive drum of this type deteriorates as a result of soiling or a deterioration of the electrostatic property of the photosensitive layer after the passage of a given period of time or after a number of copies are made. In order to prevent this deterioration in copying performance, the photosensitive drum must be removed from the casing for cleaning or replacement. The complicated internal mechanism of the apparatus, however, renders very difficult the task of removing the photosensitive drum.
To facilitate the removal and insertion of the photosensitive drum, therefore, a copier has recently been proposed having a casing which is divided vertically into two parts--upper and lower casing sections--swingably mounted on one end of each other so that the upper casing section may be swung relative to the lower casing section as required. In such a split structure, the photosensitive drum is removably mounted on the upper casing section. The photosensitive drum moves with the upper casing section as it is swung upward. In removing the photosensitive drum from the casing, therefore, the upper casing section is first swung upward to form an opening on the opposite side to the pivotal point. Then, the photosensitive drum is removed from the upper casing section through the opening.
However, the photosensitive drum in the upper casing section is surrounded by a charging unit, developing unit, cleaning unit, etc. In the removing operation, therefore, care must be taken to ensure that the photosensitive drum avoids these surrounding units. Since the photosensitive drum is disposed in the vicinity of the pivotal point positioned between the upper and lower casing sections, far from the opening or outlet, an operator must reach far into the copier to remove the photosensitive drum through the opening, which suggests an extremely unstable and strenuous operation. In consequence, an operator struggling with the photosensitive drum may be unable to prevent the drum from hitting the surrounding units and damaging them as well as the drum. Thus, the removal and insertion operations for the photosensitive drum are not only nerve racking for the operator, troublesome and inefficient.